Dear helpful forum friends,
Could you please help a novice with a vexing problem?
In a 20 gallon tank set up for 3 weeks running a Penguin Pro 125 filter at the factory setting of 125 gph
, which they say is OK for a 20 gallon tank, with an activated charcoal filter screen and an extra media bag of charcoal and resin, we have 3 fish: 2 Brilliant Rasbora and 1 Serpae Tetra. Over the 3 weeks, I used test strips twice and had a water sample tested at the pet store. There are no issues with ammonia, nitrates, nitrites, chlorine, hardness, etc ... The pH was slightly alkaline at 7.8. We may not have completed a nitrogen cycle yet. I did use the Tetra Safe Start product for the starter bacteria. We have a whole-house charcoal filter and water softener, so we don't have chlorine or metals in our tap water. We have only added 1.5 gallons to date due to evaporation and have not yet vacuumed the gravel. I did add a 1/4 dose of the Tetra AquaSafe Plus product a week ago to help their gills have a beneficial slime coat. I didn't add the full dose, because we don't have chorine issues.
One Brilliant Rasbora developed a bulging lower jaw with two catfish whisker-like protrusions over the course of week 3. It does not present as the typically described cotton beard caused by fungal problems. I attached a closeup of the sick fish and another juxtaposing the healthy fish with a normal, streamlined lower jaw below the sick fish.
As a first remedy, we're now 48 hours into a fungal treatment cycle with API's Fungus Cure product that contains Victoria Green B and Acriflavine. At 0 hours, we added a dose, removed the charcoal filtration and continued aeration. At 48 hours, we added the second dose. At 96 hours we will change 25% of the water and resume charcoal filtration.
I wonder if it is a parasite problem instead? I'd like to be smart about preserving my son's 1st pets. Of the 8 starter fish, 4 of one type and 4 of the other, we're down to 3. The first decedent at 2 days had an obvious, unrelated problem, perhaps bruising from transport. The other victims had no obvious issues. I presume they were just poor quality pet store starter fish, $1.99 each.
We had received varied advice on feeding. We may have been overfeeding from the start, but now are feeding TetraMin Tropical Fish Flakes just once per day.
The sick fish seems as active as ever. I am concerned that he hasn't demonstrated a vigorous appetite, like he had done in the past. I think the growth may hinder opening his jaw.
I'd like to solve the problem so that my son continues to think I'm smart. Thank you for your help!